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Old 7th July 2006, 04:10 AM   #21
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The way this is done is maybe 3 to 9 wires of each polarity @24 gauge (Cat5) are braided together, to cancel out noise and impedance effects. This becomes equivalent to 18 to 14 gauge wire, but as each wire is individually insulated, you have more surface effect to transmit high frequencies, and less interference, particularly if you braid the wires; and plenty of wire to carry current. At least that's the theory. I was going to use a 3 wire-pair braid from the inputs to the PCB (3+, 3-) and 6 or 9 pairs to the binding posts. I wasn't going to use this with the power supply wiring (though the AA article suggests something like it). Sometimes magnet-winding wire is used instead for this. The thinness is not supposed to be a problem, because there are multiple leads just like in twisted primary wire--but each strand is insulated, and the braiding is supposed to reduce interference and noise.

Is it totally wacko?

Anyway, yes, I am going to do the MOSFET repair first.
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Old 7th July 2006, 06:22 AM   #22
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Silpads are still for convenience. There's no thermal grease required, for serial production that'll be an interesting cost saving. There's even a silicon foil type for uneven surfaces, called GEL foil. 1/8" thick and compressable to 1/16" without glassfiber reinforcement but has poor thermal resistance. I've used some of the early silicon foil for Japanese devices with uncommon dimensions i wasn't able to get micas for, 20 years later i can but they're filthy expensive.
Nelson Pass posted some time ago that mica and thermal grease is still the ticket. The unusual white ceramic Al2-O2 flakes from Aavid Thermalloy i'm using on my Krell toaster are better than mica. Composed of 3 pieces of Aluminium Oxyde under each of the same type Japanese output devices i mentioned it renders better heat transfer than mica, a single ceramic insulator would do even better.

Personally i loathe spaghetti in amplifier cases. Neatly folded and bundled hookup wires with wire straps is nice, but braided ones have a simular efect on me as the Playboy centerfold. Make it different color braiding and you have to post a pic for other people's personal image collection. I favor teflon sleeved silver coated stranded copper hookup wire, currently waiting for several hundred feet in diff. colors and AWG sizes to arrive from ApexJr.
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Old 7th July 2006, 01:12 PM   #23
anatech is offline anatech  Canada
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Hi Michael,
Quote:
Is it totally wacko?
Yes. And braided hoses make your car go faster!

A fine strand copper cable is going to work the best, that's if the effect can be heard at all. I work with CAT-5 cable every day almost. There isn't a shred of it in any audio thing I own. I have lot's in the garage.

CAT-5 does work well for netwoking, and great for telephone wiring.

I don't care for Silpads at all, especially the compressable ones. At least mica and grease are a known quantity and they work well. In production I might use some kind of silpad type product. You can't trust workers to do a proper job these days. It's not uncommon to find crushed solder balls under transistors from the factory. Nice eh?

-Chris
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Old 7th July 2006, 02:03 PM   #24
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Michael,

The comments by Jacco and Anatech are spot on. The original article on how to POOGE the DH-200 was OK in its day. There are a few good points made in it but some of the mods it proposed were "over the top."

Look carefully at changes made between the DH-200 and DH-220. Also, look closely at the differences in parts lists between the DH-120 and the Hafler 9130 to see what I mean. Polypropylene caps in certain spots are better than mylar, metal film resistors are better than carbon resistors in many spots. But, neither will make a hearable difference when used in all spots. Also, there is a lot of snake oil sold to justify high prices for certain types of wire. I would not slavishly follow every part of the POOGE article. Plus, like it or not, there are some circuits that sound better than others and the DH-200 circuit has seen its heyday.

Also, the DH-200 circuit was laid down in the "boom and tizz" era of HiFi progress. Speakers, woofers and tweeters, have since improved to the point a more even reproduction is desirable. The DH-200 was OK for its time and still represents a fairly good value, but you can't make a silk purse out of its sows ears. This is why I stopped doing major mods to my DH-200 and installed the PCBs from Musical Concepts.

My $0.02
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Old 7th July 2006, 04:43 PM   #25
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Quote:
Originally posted by anatech
braided hoses
Highly recommended,
both for American oldfashioned displacement as for Swedish 2 cylinder boat diesels. One day i'll build a poweramp with braided hosing
Works even great on Turbo Hydraulic automatic trannies =>
Attached Images
File Type: jpg braided.jpg (25.5 KB, 188 views)
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Old 7th July 2006, 04:46 PM   #26
anatech is offline anatech  Canada
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Hi Jacco,
LMAO!
How about for liquid cooled amps? I hear poobah is using braided hoses for his high powered liquid speaker cables.

-Chris
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Old 7th July 2006, 05:57 PM   #27
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Okay, okay, I'll lose the Cat-5. Now, what am I going to do with all that extra wire in my tool shed?

It sure is a great value to be able to get the advice of those who post on this forum. Many thanks again to all of you.

Jacco, what AWG of silver-coated wire do you use when wiring amps? Do you use a different size for inputs, output to the binding posts, and power supply voltages?

I might just go to 16 AWG twisted strand Cu primary wire. The original was 18 AWG. But I will look into the silver-coated stuff--it doesn't seem so easy to find.

Dick, bottom line on the Musical Concepts mod-- Does it bring the DH-200 chassis up there with the best of what's available today? What would one I have to buy commercially to equal it?
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Old 7th July 2006, 07:13 PM   #28
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Michael,

MC sells its own branded amps and has one for around $1000 that is essentially what you would have with the MC PCBs and PS caps.

Ask around on the Madisound and Parts Express tech message boards to get opinions other than mine. Ditto over at Audio Asylum. And, do a search here at DIYaudio. The figure of $1000 is often mentioned as what one would have to pay to equal the chassis/transformer/heatsinks/MOSFETs you have with the PCB PS cap mods I recommend.

Plus, you could sell the DH-200 PCBs you now have to help defray some of the cost for the MC kit.

I give my $0.02 but ask around and understand you have to make the final decision

Here is the link for teflon covered silver plated wire that is recommended:

http://www.apexjr.com/

18 ga twisted pair is good for signal wiring and 16 ga is sufficient for PS wiring. If you do some re-wring, study how the MC mods do the ground/signal input for their PCB kits with the DH-200 chassis. Also, if you get the MC kit it will come with most of the wiring you need internally for your DH-200 chassis, plus a nice pair of RCA jacks!
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Old 8th July 2006, 04:47 AM   #29
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Quote:
Originally posted by Dick West
Michael,

...
Also, the DH-200 circuit was laid down in the "boom and tizz" era of HiFi progress. Speakers, woofers and tweeters, have since improved to the point a more even reproduction is desirable. The DH-200 was OK for its time and still represents a fairly good value, but you can't make a silk purse out of its sows ears. This is why I stopped doing major mods to my DH-200 and installed the PCBs from Musical Concepts.

My $0.02
Dick, Ihave not heard the MC circuit and can not comment on the sound and anyway one's appreciation on sound is subjective because of too many factors. I just want to say that from the pcb layout I have figured out most of the MC driver circuit and the schematics is "generally" probably an older concept than the one in the DH-200/220. However, the MC may use better components and pcb though. The latters may affect the sound positively. I suppose that upgrading some resistors and caps in the DH-220/200 could possibly bring it up to the level of the MC (and maybe more?)...... but it is only a supposition.

My $0.02 (CAN)
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Old 8th July 2006, 08:09 AM   #30
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Apex Jr.com-- Wow, what a great site! And what prices--makes you want to buy stuff, even if you don't need it or know what you're going to use it for. Even if you don't even know what it is.

Ok, it looks like we have a pro and a sort of con now on Musical Concepts. It's a discussion! Anyway, Dick, I took your advice. Posted on the Parts Express site, and read all the comments I could find on MC at the audioasylum site (there are plenty). At PE, Dick is the only poster talking about MC. Just trying to make sure you're not a shill for MC, Dick.

I have to say, but for one or two expressing disappointment on Audio Asylum, overall the comments on MC stuff are overwhelmingly positive. I could do the caps upgrades, etc myself fairly easily, but I believe what I am gathering is that John Hillig has simplified the circuit and made the sound more revealing, as well as improving components. I might follow Dick's advice on my as yet unmodded DH-200 and get the MC upgrade.
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